The present invention relates to a method and apparatus for preventing pulsations in a peristaltic fluid-infusion pump for fluid infusions.
A peristaltic type pump, for example, a peristaltic type fluid-infusion finger pump is constructed to deliver fluid inside an elastic tube by closing the tube under pressure and displacing the points of closure sequentially. When the points of closure reach the outlet port, they return to the inlet port in a peristaltic type fluid-infusion finger pump. When the points of closure return to the inlet port, the closure under pressure at the outlet port is released. Due to the relative positions of the inlet and outlet ports, the fluid inside the tube is spontaneously displaced independently of the operation of the pump. Thus, a general peristaltic type fluid-infusion finger pump is so constructed that at least one point of closure is present at all times. Although the fluid infusion is continuously performed while the points of closure are sequentially displaced as described above, the fluid delivery is interrupted when the closure under pressure is released at the outlet port. Furthermore, with a fluid-infusion finger pump, the pressure plate is slightly vibrated in the front-back direction, and fine pulsations are caused when the point of closure changes from one finger to the other. It is preferable that the fluid be continuously delivered at a constant flow rate in fluid infusions. Thus, a peristaltic type fluid-infusion pump which does not cause pulsations has been desired.